Function definition in Lua

Question

Is there any difference between

local splitPathFileExtension = function (res)
end

and

function splitPathFileExtension(res)
end

? I understand in the first case this function is anonymous but this is the only difference?

Answer 1

They are almost exactly the same thing (other than the fact that you've specified the first function as local and not the second one.)

See the manual on function definitions:

The statement

    function f () body end

corresponds to

    f = function () body end

The statement

    function t.a.b.c.f () body end

translates to

    t.a.b.c.f = function () body end

The statement

    local function f () body end

translates to

    local f; f = function () body end

not to

    local f = function () body end

(This only makes a difference when the body of the function contains references to f.)

Answer 2

All functions are anonymous, they don't have names. A function definition is in fact an assignment statement that creates a value of type function and assigns it to a variable.

The second code is syntactic sugar that's equivalent to:

splitPathFileExtension = function (res) end

So, other than the first is local while the second is global, there's no difference between the two ways of function definition.